Olefin Block Copolymers (OBC) can exhibit a unique balance of flexibility-heat resistance-recovery properties. In particular, the high temperature compression set properties of OBCs with ethylene crystallinity are comparable to or exceed those of the incumbent materials such as f-PVC and SEBS for profile and gasket applications. However, it would be desirable to improve the rheology of these polymers for melt processability of extruded profiles, gaskets, foams etc. Several options have been explored to improve melt rheological behavior of OBCs to allow improved use in extruded profile applications, such as peroxide modification and E-beam crosslinking, such as described in U.S. Pat. No. 7,795,321. Branching of OBCs has been disclosed in US Patent Application Publication No. 2009/0163667.
Comb polymers, in general, have been previously described in, for example, “Metallocene-Based Branch-Block Thermoplastic Elastomers” Eric J. Markel, et al, Macromolecules, 2000, 33 (23), 8541-8548, “Characterization and Modeling of Metallocene-Based Branch-Block Copolymers” Armenag H. Dekmezian, et al, Macromolecules, 2002, 35 (25), 9586-9594, U.S. Pat. No. 6,423,793, U.S. Pat. No. 6,147,180, and U.S. Pat. No. 6,444,773.
It would be advantageous to provide comb architecture olefin block copolymers (C-OBCs) with improved properties.